The invention relates to a method of producing metals or metal alloys by reducing their halides as well as to an arrangement for carrying out the method.
The recovery of metals from their halides is particularly known for titanium, zircon, hafnium, niobium and tantalum. It may, however, also be used for other metals, such as, e.g., chromium and uranium. For the production of titanium the so-called Kroll method according to U.S. Pat. No. 2 205 854, is known, in which as starting materials, titanium tetrachloride and a reducing metal, namely magnesium or sodium, are used, and the titanium tetrachloride is introduced in the gaseous or the liquid form into a reaction crucible filled with a liquid reducing metal. The temperature is maintained at about 1100.degree. K. Disadvantages of this method are that the reducing metal is expensive, the recovery of the metal from the metal halide is complex and the titanium is obtained in sponge form, thus requiring several steps of after-treatment.
A similar method is described in German Offenlegungsschrift No. 30 24 697, in which the reduction of the titanium tetrachloride is effected by the common action of sodium and hydrogen at temperatures of about 3000.degree. K. The heat required for maintaining this temperature is obtained by exothermal reaction of the titanium tetrachloride with the reducing metal sodium, on the one hand, and, on the other hand, is produced by heating with an electric arc, a mirror burner, laser beams, or with plasma burners directed to the reaction zone. This method, too, has certain disadvantages, i.e. the use of the expensive reducing metal sodium and the great amount of energy necessary for vaporizing this reducing metal. Furthermore, problems result at the start, because measures must be taken which are difficult to carry out from the viewpoint of process technology in order to prevent obstructions of the supply ducts caused by the mutual diffusion of the reaction partners.
From German Auslegeschrift No. 1,295,194, a method for producing tantalum and/or niobium metal is known, in which the metal chlorides are introduced in solid form into a hydrogen plasma in the presence of a condensed dispersed heavy-metal carbide, with the reduced tantalum and/or niobium depositing on the heavy-metal carbide particles. This method is, however, not suited to be carried out on a technological scale.